SINGAPORE — Three types of metformin diabetes medications are being recalled after they were found to contain trace amounts of an impurity, the Health Sciences Authority (HSA) said on Thursday (Dec 5).

The affected medications are one batch of Glucient XR 500mg tablets supplied by Glorious Dexa Singapore and all batches of the 750mg and 1000mg versions of Meijumet Prolonged Release, supplied by Pharmazen Medical.

All three drugs were found to contain amounts of a type of nitrosamine impurity — known as N-nitrosodimethylamine (NDMA) — above the internationally acceptable level.

HSA said that it has tested all 46 locally marketed metformin medicines and found that the other 43 drugs were not affected.

HSA added that the risk to patients who have been taking the three affected metformin medicines is “very low”.

“This is because the potential risk of nitrosamines is associated with long-term use, and the three affected medicines have only been supplied locally for a short period of time since last year.”

NDMA is commonly found in low levels in processed food such as pickled vegetables, salted fish and processed meat products such as bacon and sausages. It is also found in the environment and is present in air pollution.

Nitrosamine impurities have also recently been found to have formed unexpectedly during the manufacture of some medicine.

PATIENTS SHOULD NOT STOP TAKING MEDICATION

Patients taking the affected metformin medicines are advised not to stop treatment on their own, as the sudden stopping of medicines will raise blood sugar levels, which may pose a greater health risk.

Healthcare professionals have been advised by HSA to contact their affected patients to arrange for an exchange of their medicines as soon as possible. Patients who are concerned about their current treatment can speak to their doctor or pharmacist.

HSA said that it is also working with the companies supplying these medicines as well as international regulatory agencies to verify the causes of the contamination, and to address the issue.

According to HSA, worldwide recalls have been conducted for the affected products.

Acceptable levels of nitrosamines are set in nanograms and is based on what is considered as reasonably safe if a patient continues to take the affected medicine every day for a lifetime of 70 years.

For example, the added cancer risk from an additional six-month exposure is estimated to be less than 0.00002 per cent.

“The additional risk posed by NDMA from metformin, at the levels detected, is considered very low,” HSA said. CNA

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